1. Field of the Invention
The present invention relates to an apparatus and method for efficiently operating a fast feedback channel in a wireless communication system. More particularly, the present invention relates to an apparatus and method for efficiently allocating and deallocating a fast feedback channel in a case of operating a plurality of fast feedback channels per Mobile Station (MS) in a wireless communication system based on an Orthogonal Frequency Division Multiple Access (OFDMA) scheme.
2. Description of the Related Art
In the 4th Generation (4G) communication system, which is the next generation communication system, research is being conducted to provide users with services of various Quality of Service (QoS) at a data rate of about 100 Mbps. In particular, a study of the 4G communication system is being made to support high-speed services in considering the guarantee of mobility and QoS for a Broadband Wireless Access (BWA) communication system such as a Wireless Local Area Network (WLAN) system and a Wireless Metropolitan Area Network (WMAN) system. A typical 4G communication system is an Institute of Electrical and Electronics Engineers (IEEE) 802.16 system. The IEEE 802.16 system is a communication system applying an Orthogonal Frequency Division Multiplexing/OFDMA (OFDM/OFDMA) scheme to support a broadband transmission network in a physical channel.
The typical IEEE 802.16m wireless communication system based on the OFDMA scheme uses a control signal of a Feedback Allocation Advanced-MAP Information Element (Feedback Allocation A-MAP IE) in order to command the allocation and deallocation of a fast feedback channel for a Mobile Station (MS). Presently, the Feedback Allocation A-MAP IE may manage one fast feedback channel. In case of allocating a new fast feedback channel, a Base Station (BS) forwards a feedback period, an allocation duration, a physical position of the fast feedback channel, the kind of feedback information to transmit through the fast feedback channel, etc. through a Feedback Allocation A-MAP IE. Here, the kind of the feedback information is determined through a ‘Multiple Input Multiple Output (MIMO) Feedback Mode (MFM)’ field.
The deallocation of an existing allocated fast feedback channel may be achieved through two schemes. The first scheme is a scheme in which an ‘allocation duration’ field is set to a specific duration within a Feedback Allocation A-MAP IE at the time of allocating a fast feedback channel and, when the allocation duration is ended, the fast feedback channel is automatically deallocated. The second scheme is a scheme in which a fast feedback channel is forcibly deallocated by a BS. This is achieved by newly transmitting and receiving a Feedback Allocation A-MAP IE whose ‘allocation duration’ field is set to ‘0b000’.
The standard of the present D3 criterion has a structure in which an existing allocated fast feedback channel is automatically deallocated when a new fast feedback channel is allocated through a Feedback Allocation A-MAP IE. That is, the D3 criterion standard has a limitation in which only one fast feedback channel per MS exists. If this limitation disappears so that a plurality of fast feedback channels may be operated, a process of deallocation of a fast feedback channel, allocation of a new fast feedback channel, and the like, becomes inefficient. That is, if a plurality of fast feedback channels previously allocated to an MS exist and a BS intends to deallocate some or all of the fast feedback channels, the BS should transmit as many Feedback Allocation A-MAP IEs as the number of the fast feedback channels intended to be deallocated, to inform of the deallocation on a per channel basis. Also, if the BS intends to allocate a new fast feedback channel, the BS should once again transmit a Feedback Allocation A-MAP IE informing of the new allocation.
Thus, there is a need to propose a scheme of efficiently allocating and deallocating a fast feedback channel in a case in which a plurality of fast feedback channels per MS are operated in a wireless communication system based on an OFDMA scheme.